use std::cmp;
use std::collections::BinaryHeap;

struct Solution {}
impl Solution {
    pub fn furthest_building(heights: Vec<i32>, mut bricks: i32, mut ladders: i32) -> i32 {
        let mut used: BinaryHeap<i32> = BinaryHeap::new();

        let mut idx = 0;
        while idx + 1 < heights.len() {
            let h_diff = heights[idx + 1] - heights[idx];

            // no reason to use ladder or bricks
            if h_diff <= 0 {
                idx += 1;
                continue;
            }

            // by default use the bricks
            bricks -= h_diff;
            used.push(h_diff);

            // if we run out of bricks, use ladder
            // for the biggest “skip” that used bricks
            if bricks < 0 {
                bricks += used.pop().expect("we used some bricks");
                ladders -= 1;
            }

            if ladders < 0 {
                break;
            }

            idx += 1;
        }

        idx as i32
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn example_1() {
        assert_eq!(
            Solution::furthest_building(vec![4, 2, 7, 6, 9, 14, 12], 5, 1),
            4
        );
    }

    #[test]
    fn example_2() {
        assert_eq!(
            Solution::furthest_building(vec![4, 12, 2, 7, 3, 18, 20, 3, 19], 10, 2),
            7
        );
    }

    #[test]
    fn example_3() {
        assert_eq!(Solution::furthest_building(vec![14, 3, 19, 3], 17, 0), 3);
    }

    #[test]
    fn tle_1() {
        assert_eq!(
            Solution::furthest_building(
                vec![
                    253710, 459585, 71981, 223232, 977918, 148680, 123527, 250812, 260416, 554767,
                    473621, 88538, 966794, 644116, 865416, 590993, 550004, 374573, 105036, 568303,
                    460987, 24602, 757598, 519047, 263800, 315868, 963895, 266638, 598245, 713310,
                    489802, 364169, 742274, 973483, 807739, 253747, 564636, 472387, 598445, 675408,
                    626061, 527760, 922748, 244691, 41163, 108095, 953208, 54400, 191957, 182321,
                    801110, 526756, 11220, 560896, 782344, 565351, 570890, 931781, 511665, 108738,
                    357367, 853555, 674526, 388790, 686349, 554731, 102668, 335287, 461231, 496065,
                    489980, 525209, 693696, 140598, 784402, 564477, 743153, 156379, 370768, 94810,
                    121932, 338323, 972441, 553422, 865236, 627884, 673412, 16147, 858309, 802780,
                    150410, 657225, 761430, 916149, 644587, 364929, 661236, 207648, 507409, 209803,
                    663553, 296241, 51843, 758342, 448408, 310536, 733500, 390516, 580506, 313748,
                    729366, 961156, 766804, 752158, 713426, 946971, 433800, 611365, 806559, 950149,
                    831368, 871881, 132092, 644626, 150762, 487527, 365094, 316637, 684249, 740162,
                    605893, 272845, 416251, 905202, 984909, 602362, 424697, 686193, 566240, 159584,
                    600277, 767037, 211677, 441897, 586509, 965864, 393340, 497044, 881539, 145921,
                    159055, 866123, 603476, 657682, 284714, 85306, 470415, 534245, 641462, 472616,
                    159434, 421500, 843442, 634366, 625668, 444943, 657933, 129173, 914540, 215272,
                    598415, 457087, 437568, 490742, 172811, 212016, 435680, 599042, 789308, 279873,
                    689943, 369130, 618428, 524390, 877649, 118759, 60586, 37618, 20797, 492854,
                    946585, 583767, 944693, 62988, 358292, 708659, 23496, 966718, 557539, 131703,
                    358231, 215464, 771609, 375770, 855917, 147866, 543477, 786910, 760512, 468183,
                    542081, 373398, 979543, 126508, 361409, 842847, 872593, 746682, 893518, 457222,
                    978730, 161753, 697245, 205997, 363180, 807952, 795175, 808090, 462585, 658667,
                    186220, 858457, 923762, 700792, 294201, 584816, 514737, 261038, 327627, 205592,
                    221896, 444108, 979369, 129394, 44001, 790354, 353917, 72772, 330118, 360651,
                    635275, 849492, 966042, 843108, 158554, 406317, 995111, 147752, 121006, 486157,
                    678653, 217657, 4288, 573547, 820817, 164534, 921608, 308037, 373838, 385901,
                    343399, 813472, 58859, 346176, 68090, 539503, 322652, 958331, 832724, 585003,
                    75794, 228299, 31211, 302603, 601041, 362034, 300803, 347024, 650585, 172193,
                    876895, 603734, 165956, 796982, 786231, 738823, 562729, 158032, 364908, 988395,
                    775023, 671485, 424571, 572157, 623273, 772919, 914302, 661979, 920229, 614760,
                    934156, 511607, 889533, 382154, 82654, 973121, 549095, 639792, 412821, 305216,
                    74071, 571794, 969979, 932469, 335153, 898442, 938912, 729489, 872970, 874332,
                    8390, 345366, 901364, 245104, 315592, 895028, 533836, 427909, 737421, 161915,
                    510434, 768573, 179267, 237370, 562023, 650593, 869876, 544314, 464374, 701215,
                    789191, 746271, 871247, 385836, 788092, 890101, 286938, 367130, 635751, 295576,
                    607054, 913206, 556383, 512305, 253121, 461980, 951444, 192012, 897432, 140517,
                    842228, 924286, 268918, 765459, 344159, 347853, 592899, 247814, 379693, 421908,
                    295638, 672994, 774285, 78096, 886320, 998456, 10915, 581642, 549650, 905526,
                    186991, 586693, 320053, 829130, 465779, 191060, 238711, 415584, 273709, 35854,
                    55818, 305798, 667280, 334370, 121051, 665390, 230729, 51662, 904228, 971349,
                    7088, 567705, 265941, 380847, 760602, 280222, 351148, 518112, 609328, 381795,
                    46766, 301829, 886537, 338310, 130937, 813816, 446885, 126867, 578861, 996302,
                    56516, 316900, 648733, 457604, 903338, 974707, 336231, 878687, 776626, 583241,
                    353383, 591761, 438716, 892530, 231901, 959454, 915103, 50735, 453313, 519651,
                    940657, 68380, 38339, 339705, 19207, 844122, 483005, 582959, 592635, 870233,
                    208322, 862826, 598864, 989646, 583679, 219396, 371194, 111781, 493739, 313465,
                    383867, 545219, 171577, 761747, 992356, 973874, 497603, 976481, 136374, 138311,
                    918066, 787696, 929197, 589326, 801358, 944697, 28038, 211029, 752621, 210197,
                    491050, 939207, 254024, 145811, 767376, 922553, 796100, 15858, 899164, 950319,
                    728378, 563113, 532136, 705190, 290216, 359946, 214594, 327241, 641000, 385347,
                    786200, 700340, 576438, 227606, 498337, 451637, 425192, 286305, 472053, 335562,
                    587556, 683468, 290205, 997253, 868480, 320419, 392391, 128015, 674737, 410783,
                    136490, 46713, 154232, 574917, 904387, 99900, 490640, 268209, 994867, 135705,
                    390652, 412028, 404195, 490553, 184029, 624391, 836288, 619242, 570500, 367786,
                    908994, 934572, 226481, 281181, 469810, 376226, 354931, 55711, 43299, 487568,
                    853741, 556475, 842100, 133451, 371270, 820314, 735709, 859169, 992745, 981261,
                    506744, 573542, 544798, 335063, 71332, 345306, 551165, 522500, 148531, 323820,
                    525891, 571989, 109699, 540927, 391815, 383139, 528328, 941384, 577084, 148432,
                    537377, 589708, 613443, 589827, 688798, 501198, 304829, 719726, 181892, 891384,
                    237429, 447803, 49953, 555945, 69576, 765896, 194628, 866362, 533750, 798399,
                    369884, 258270, 964160, 796047, 420697, 486470, 781692, 825420, 689886, 392317,
                    278581, 151823, 184594, 295461, 723312, 604322, 248126, 43623, 91154, 600821,
                    55136, 709242, 990838, 263827, 564093, 735641, 174057, 932157, 750399, 807534,
                    338221, 830644, 171022, 156968, 351523, 814982, 403402, 975555, 955973, 400091,
                    523040, 382185, 577810, 257717, 544345, 243199, 509472, 450948, 839442, 387377,
                    553239, 145202, 822954, 478559, 487143, 514465, 587609, 575770, 547307, 386320,
                    410846, 81519, 599793, 874316, 730403, 913822, 800625, 96868, 913119, 843783,
                    699, 767204, 432828, 496436, 348230, 767865, 455134, 266270, 324004, 863226,
                    758456, 66451, 431182, 641607, 514915, 522399, 164590, 335706, 829719, 724524,
                    981933, 812770, 192582, 880771, 71867, 704720, 691726, 761694, 868674, 964177,
                    287148, 124076, 155241, 535262, 856554, 108951, 453851, 597675, 592745, 32413,
                    774791, 750298, 66826, 876820, 567338, 699491, 336474, 60148, 776819, 430070,
                    546456, 564666, 776689, 886534, 68830, 749993, 157504, 933346, 39836, 417088,
                    481438, 30183, 515310, 764031, 876787, 321614, 765291, 466180, 941767, 877507,
                    658149, 60699, 413225, 849839, 376668, 689777, 491763, 712459, 5768, 608757,
                    161358, 554199, 132368, 464770, 89566, 309794, 430979, 979239, 62376, 354441,
                    582188, 947427, 569030, 430121, 826059, 562654, 461350, 901008, 191328, 484599,
                    615686, 859104, 366550, 140695, 229053, 282037, 289028, 296120, 883539, 980557,
                    365526, 143257, 658629, 730361, 683520, 101817, 442395, 50455, 199765, 137552,
                    653983, 47041, 102020, 308470, 523274, 447051, 345263, 967056, 525031, 506873,
                    170405, 995568, 977216, 83193, 279492, 376521, 946443, 847471, 845107, 321145,
                    866307, 523882, 135730, 824806, 927733, 605908, 580895, 177233, 443804, 914175,
                    905847, 661407, 483093, 518439, 789231, 66585, 447439, 14824, 861841, 89137,
                    913636, 194682, 166773, 212398, 259259, 160638, 435374, 941416, 140851, 311224,
                    54813, 155003, 595354, 742575, 668942, 77310, 96783, 217826, 211522, 116834,
                    391751, 922905, 730508, 225636, 265187, 995541, 329461, 244649, 951125, 322487,
                    140958, 608238, 511144, 410963, 335698, 228967, 487748, 382037, 261094, 363854,
                    557078, 539851, 519352, 364988, 444038, 284404, 730251, 828294, 608545, 188095,
                    466810, 46659, 673970, 142329, 93794, 167913, 30119, 116528, 592075, 810599,
                    14144, 445947, 51745, 236481, 878706, 838520, 310352, 112640, 612690, 663852,
                    546444, 818881, 868195, 573845, 390221, 254379
                ],
                33671263,
                108
            ),
            589
        );
    }
}