39 lines
815 B
C++
39 lines
815 B
C++
#include <functional>
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/**
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* 52. N-Queens II
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* The n-queens puzzle is the problem of placing n queens on an n x n chessboard such that no two queens attack each other.
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* Given an integer n, return the number of distinct solutions to the n-queens puzzle.
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*/
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class Solution {
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public:
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static int totalNQueens(int n) {
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int ret = 0;
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bool xs[10]{}, ds[20]{}, sds[20]{}, G[10][10]{};
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std::function<void(int)> dfs = [&](int d) {
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if (d >= n) {
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++ret;
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return;
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}
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for (int i = 0; i < n; ++i) {
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if (xs[i] || ds[d - i + 10] || sds[d + i])
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continue;
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G[d][i] = xs[i] = ds[d - i + 10] = sds[d + i] = true;
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dfs(1 + d);
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G[d][i] = xs[i] = ds[d - i + 10] = sds[d + i] = false;
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}
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};
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dfs(0);
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return ret;
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}
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};
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int main() {
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auto ret = Solution::totalNQueens(4);
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return 0;
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}
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