48 lines
1.1 KiB
C++
48 lines
1.1 KiB
C++
#include <cassert>
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#include <vector>
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class Solution {
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struct indices {
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int x;
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int y;
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bool operator==(const indices &other) const = default;
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indices &operator+=(const indices &other) {
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x += other.x;
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y += other.y;
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return *this;
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}
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int operator[](const std::vector<std::vector<int>> &mat) const {
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return mat[y][x];
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}
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};
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public:
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int diagonalSum(const std::vector<std::vector<int>> &mat) {
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int sum = 0;
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indices down{0, 0}, up{0, static_cast<int>(mat.size()) - 1};
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indices d_down{1, 1}, d_up{1, -1};
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for (std::size_t i = 0; i < mat.size();
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++i, down += d_down, up += d_up) {
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sum += down[mat];
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if (down != up) {
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sum += up[mat];
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}
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}
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return sum;
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}
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};
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int main() {
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Solution s;
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assert((s.diagonalSum({{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}) == 25));
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assert(
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(s.diagonalSum(
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{{1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}, {1, 1, 1, 1}}) == 8));
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assert((s.diagonalSum({{5}}) == 5));
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return 0;
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}
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