Merge pull request youngyangyang04#804 from KingArthur0205/remote

添加0046.全排列.md C语言版本

Author: youngyangyang04

problems/0046.全排列.md

@@ -309,6 +309,72 @@ var permute = function(nums) {
 
 ```
 
+C:
+```c
+int* path;
+int pathTop;
+int** ans;
+int ansTop;
+
+//将used中元素都设置为0
+void initialize(int* used, int usedLength) {
+    int i;
+    for(i = 0; i < usedLength; i++) {
+        used[i] = 0;
+    }
+}
+
+//将path中元素拷贝到ans中
+void copy() {
+    int* tempPath = (int*)malloc(sizeof(int) * pathTop);
+    int i;
+    for(i = 0; i < pathTop; i++) {
+        tempPath[i] = path[i];
+    }
+    ans[ansTop++] = tempPath;
+}
+
+void backTracking(int* nums, int numsSize, int* used) {
+    //若path中元素个数等于nums元素个数，将nums放入ans中
+    if(pathTop == numsSize) {
+        copy();
+        return;
+    }
+    int i;
+    for(i = 0; i < numsSize; i++) {
+        //若当前下标中元素已使用过，则跳过当前元素
+        if(used[i])
+            continue;
+        used[i] = 1;
+        path[pathTop++] = nums[i];
+        backTracking(nums, numsSize, used);
+        //回溯
+        pathTop--;
+        used[i] = 0;
+    }
+}
+
+int** permute(int* nums, int numsSize, int* returnSize, int** returnColumnSizes){
+    //初始化辅助变量
+    path = (int*)malloc(sizeof(int) * numsSize);
+    ans = (int**)malloc(sizeof(int*) * 1000);
+    int* used = (int*)malloc(sizeof(int) * numsSize);
+    //将used数组中元素都置0
+    initialize(used, numsSize);
+    ansTop = pathTop = 0;
+
+    backTracking(nums, numsSize, used);
+
+    //设置path和ans数组的长度
+    *returnSize = ansTop;
+    *returnColumnSizes = (int*)malloc(sizeof(int) * ansTop);
+    int i;
+    for(i = 0; i < ansTop; i++) {
+        (*returnColumnSizes)[i] = numsSize;
+    }
+    return ans;
+}
+```
 
 
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