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https://git.sb/baoshuo/OI-codes.git
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88 lines
1.6 KiB
C++
88 lines
1.6 KiB
C++
#include <iostream>
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#include <iomanip>
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using std::cin;
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using std::cout;
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const char endl = '\n';
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const int N = 55;
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const double eps = 1e-6;
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int n;
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double a[N][N];
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int gauss() {
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int r, c;
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for (r = c = 1; c <= n; c++) {
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int t = r;
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for (int i = r; i <= n; i++) {
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if (std::abs(a[i][c]) > std::abs(a[t][c])) t = i;
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}
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if (std::abs(a[t][c]) < eps) continue;
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std::swap(a[t], a[r]);
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for (int i = n + 1; i >= c; i--) {
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a[r][i] /= a[r][c];
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}
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for (int i = r + 1; i <= n; i++) {
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if (std::abs(a[i][c]) > eps) {
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for (int j = n + 1; j >= c; j--) {
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a[i][j] -= a[i][c] * a[r][j];
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}
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}
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}
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r++;
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}
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if (r <= n) {
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for (int i = r; i <= n; i++) {
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if (std::abs(a[i][n + 1]) > eps) {
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return -1;
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}
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}
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return 1;
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}
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for (int i = n; i; i--) {
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for (int j = i + 1; j <= n; j++) {
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a[i][n + 1] -= a[i][j] * a[j][n + 1];
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}
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}
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return 0;
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}
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int main() {
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std::ios::sync_with_stdio(false);
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cin.tie(nullptr);
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cin >> n;
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for (int i = 1; i <= n; i++) {
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for (int j = 1; j <= n + 1; j++) {
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cin >> a[i][j];
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}
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}
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int r = gauss();
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if (r == 1) {
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cout << 0 << endl;
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} else if (r == -1) {
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cout << -1 << endl;
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} else {
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for (int i = 1; i <= n; i++) {
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cout << 'x' << i << '=' << std::fixed << std::setprecision(2) << (std::abs(a[i][n + 1]) < eps ? 0.0 : a[i][n + 1]) << endl;
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}
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}
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return 0;
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}
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